splitting - an alternate method

by John Bokstrom

Here is a method for easier splitting. It produces strips of minimum width and therefor more strips from each culm. These narrow strips require less planing and are easier to straighten at the nodes. Also, with a little extra care, nodes can be kept away from critical areas at the tip and ferrules.

keeping nodes away from tip and ferrules:

The key here lies in selecting a culm with good node spacing for the length of rod to be made. Ray Gould pointed out at the Corbett Lake meeting in 1990 that despite Mr. Garrison's typical stress curves which show maximum stress at the extreme tip of the rod, his practice of redrawing the top five inches (page 272) moves the maximum to the 5 inch point. Many other tapers, particularly of small rods, show similar re-drawing. It is clearly a good idea to keep nodes well away from the tip and the five inch point.

It is also a good idea to keep nodes away from the ferrule, particularly the male. Many tapers have a step-up at the ferrule which focuses stresses right there. Stiff butts further compound the problem. This is not to imply that rods with nodes near the tip or near the ferrule are disasters, only that caring for these details can make a good rod even better.

selecting a culm:

If you follow the common practice of utilizing the lower portion of the culm for butt material and the portion above that for tip material, the nodes will probably not fall in the best locations with regard to the tip and ferrules. However, if you think of the ferrule end of the butt material as falling just before the first node above the butt splitting length, then you'll have the maximum of node-free bamboo at the female ferrule. If this node and immediate area, about three inches total, is cut away, then the tip will have the maximum of node-free bamboo for the male ferrule. The first step then is to locate this node.

A whole culm of bamboo

The second step, the most important in our selection process, is to measure the tip section of the culm from the other side of the node in order to determine the upper end of the tip.. If this point is 2 to 4 inches below another node, you have a suitable culm. If not, try another culm. When you find one that is suitable, cut out and discard the node that fell between the butt and tip pieces, discard the off-cut below the butt piece and the off-cut above the tip piece. Now you will have butt strips and tip strips than can be staggered without fear of nodes being too near tips or ferrules.

If such a suitable culm is not available, keeping nodes away from the tip deserves priority. Add the splitting lengths for butt and tip together and, laying a tape measure along the culm, see where the cut-off point for the tip would fall. If this point does not give you sufficient node-free bamboo to allow for leeway and staggering, slide the whole tape up the culm to place the cut-off point just below the next higher node. The internodal spaces in this area of most culms are 18 inches or better, more than enough after staggering to keep nodes away from the tip top and the 5 inch mark. Mark this point and measure back down the culm to mark your other two cuts. Discard the off-cut at the butt end. If you feel that by doing this you are into thinner power fibers, you always have the option of adding .001" or .002" to each station along the rod.